#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#define oops(s,x) { perror(s); exit(x); }
int main(int argc, char *argv[])
{
struct termios info;
if ( argc == 1 )
exit(0);
if ( tcgetattr(0,&info) == -1 ) /* get attribs */
oops("tcgettattr", 1);
if ( argv[1][0] == 'y' )
info.c_lflag |= ECHO ; /* turn on bit */
else
info.c_lflag &= ~ECHO ; /* turn off bit */
if ( tcsetattr(0,TCSANOW,&info) == -1 ) /* set attribs */
oops("tcsetattr",2);
return 0;
} 
